Electrical interlock



Nov. 13, 1962 B. c. WELLS ETAL ELECTRICAL INTERLOCK 2 Sheets-Sheet 1Filed Aug. 7, 1959 INVENTORS Donald D. Armstrong 8 Bruce C. Wells.

BY M ATTORNEY gill-28,2182 X W Nov. 13, 1962 B. c. WELLS ETAL ELECTRICALINTERLOCK 2 Sheets-Sheet 2 Filed Aug. 7, 1959 rangement, the arc blowoutfeatures and the United States This invention relates to electricswitches and more particularly to interlock type contacts, and auxiliaryswitches, for use on an electromagnetic contactor to be actuated by themagnetic armature, or other actuating member, of such contactor.

Interlock contact devices are well known in the art wherein the contactarrangement is such that one and the same unit can operate as a makecontact or as a break contact.

It is one specific object of this invention to provide an improvednon-polarized contact device which combines, with a single unit thatprovides selectively make and break operation, a permanent magnetblowout system to extinguish the are together with a. double-breakcontact arrangement.

It is a further specific object of this invention to provide, in aswitching arrangement wherein a bridging member bridges a pair of spacedstationary contacts and wherein either circuit closure or circuitinterruption is simultaneously effected at two separate spaced points,for independent arc blowout means functioning simultaneously butindependently at two separate points in a circuit.

It is a further object of this invention to provide an interlock that isreadily convertible from a normally open to a normally closed switch,and vice versa, and that is also compact, rugged, and small, yet capableto interrupt much larger currents than prior art devices of the samesize, thus avoiding the need for interposing relays in circuitscontaining multiple, or large, contactor coils.

It is a specific object of this invention to provide a closed insulatedconstruction, except for the region where circuit connections are to bemade, which thus simplifies installation since electrical creepage andare striking distances need not be considered in mounting the interlock.

The objects recited are merely illustrative. Other objects and featuresof this invention will become more apparent from the embodiment shown bythe drawings, in which:

FIGURE 1 is a perspective view of the contact aractuator assembly allshown disassociated from the housing;

FIG. 2 is a showing of the invention from the side with the front halfof the housing removed, and showing the interlock contacts arranged as anormally open switch;

FIG. 3 is a showing like FIG. 2 but with the contacts arranged as anormally closed switch;

FIG. 4 is a showing of the interlock on section line IV-IV of FIG. 2;

FIG. 5 is a showing of the interlock on section line VV of FIG. 2; and

FIG. 6 is a showing of a portion of the interlock, the section beingtaken on line VI-VI of FIG. 2.

The showings in FIGS. 4, 5 and 6 are made on the.

assumption that both halves of the housing are in position.

In the drawings the switching unit is shown enclosed in a housingcomprising two identical moldings, or side members, 1 and 2 ofinsulating material. Two iron pole pieces, or shoes, 3 and 5 are moldedin member 1 and two iron pole pieces, or shoes, 4 and 6 are molded inside member 2.

The two side members 1 and 2 are provided with matching holes havingrecesses, at their outer ends so that eyelets, or hollow rivets, as HRmay be used to rivet the parts together as shown in FIG. 4. Since therivets are hollow, bolts may be inserted through the holes and anynumber of interlocks stacked together and rigidly mounted on thecontactor with which the interlock coacts.

The two side members together are so shaped as to provide recesses forthe relatively short cylindrical ceramic permanent magnets 7 and 8 ofinsulating material. The ends of the magnets fit snugly up against thepole shoes and the arrange ent is such that like poles of the magnetsare directed in opposite directions. The pole shoes are fiat cylindricalmembers and are eccentrically disposed with reference to the magnets sothat pole shoes 3 and 4 straddle the stationary contact 9 and pole shoes5 and 6 straddle the stationary contact 10.

These contacts and 10 are silver buttons each fastened to a copper strapas the straps 11 and 12, respectively. Strap It is bent around magnet 7and strap 12 is bent around magnet 3 to thus form are horns around eachof the magnets. This construction aids in arc lengthening and thus inarc blow out and since each stationary contact has its own magnet andarc horn, two separate and independently functioning blowout structures,are provided. The outer ends of the straps 11 and 12 are provided withthe terminal screw arrangements l3 and 14, respectively.

At the bottom center, the two members are so shaped to provide a squarehole to slidably engage the squarein-section lower end of the plunger,or push rod 19. The upper end of the rod is shaped as shown and fitsthrough a matching opening in the housing. The plunger may thus be movedalong its axis in the housing, but can not rotate about its axis.

The plunger has a frame shaped middle portion 20. A contact member 15 isseated in the bottom end of the frame, and has two silver contactbuttons 17 and 18 engageable with the stationary contact buttons 9 and10, respectively, for electrically bridging the two contact straps 11and 12.

The engagement between contact member 15 and the bottom portion of theframe portion 20 of the plunger is such, as shown, that contact 15 isprevented from revolving relative to the plunger but can slide axially.A positioning, or back-u member 21 is seated in the top end of the frameand is also axially movable in the frame. The positioning member hassectors cut out at the edge so that it may also be angularly moved aboutthe plunger axis through a selected angle. In FIGS. 1, 2 and 4, thepositioning member is shown in its upper position with reference to thehousing.

A helical compression spring 22 is disposed between the positioningmember 21 and the contact 15 and biases them away from each other towardthe respective axial sides of the frame 20 which thus act as stops.Another helical compression spring 23 is disposed on the plunger betweenthe bottom of a Well 24 in the housing and the cylindrical portion 25 ofthe plunger. In the assembled condition of the device the spring 22 isstronger than spring 23 at least when spring 22 is in the compressedcondition as shown in FIG. 3.

The side members 1 and 2 at the upper boundaries of the side holes areprovided with oppositely disposed notches 26 and 27 for receiving andretaining in position the outer rounded ends 28 and 29 of the back-upmember. When the ends 28 and 29 are in the notches 26 and 27, as shownin FIG. 2, the interlock is a normally open switch.

The side members 1 and 2 are provided with oppositely disposed lowernotches 30 and 31. When the ends 28 and29 are in the notches 30 and 31,the interlock is a normally closed switch as shown in FIG. 3. Thechange-over is made by depressing 21 and moving it clock-wise, it seenfrom the top, until the ends fit into the notches. than in the showingin PEG. 2. The interlock is turned around on the, contactor so thatactuating of the contactor, not shown, operates the interlock byengaging the lower end of the plunger 19. i

Regardless of the manner of use made of the interlock, namely as anormally open switch or a normally closed switch, interruption'of thecircuit occurs simultaneously at 9 and 17, and 1t) and 18 and the arcsare rapidly Spring 23 will be more compressed moved along each arc hornby the permanent magnets and are rapidly extinguished; Since the archorns extend to both sides of the, fixed contacts, interruption isindependent of the current polarity. Further, since the magnets aremounted with the same poles directed in opposite directions, onearcblows toward and the other away from the push rod 19. Further, thekickout Spring 23 is hooded, that is, being disposed ina well with thecylindrical portion 25 closing the well, it is protected against theinward moving arc.

, While but one embodiment of this invention has been disclosed, otherarrangements are possible, all falling within the spirit of thisinvention. i

We claim as our invention: 1. An electric switch comprising, a housing,a plunger slidably mounted in said housing, a spring biased elongatedcontact mounted transversely of the plunger on the plunger to move withmovement of the plunger, a pair of stationary contacts mounted in thehousing, one stationary contact'being disposed at one side of theplunger and the other at the other side of the plunger and so disposedwith reference to the elongated contact and the plunger that movement ofthe plungeor in onedirection causes circuit closure at each of thestationary contacts and movement of the plunger in an opposite directioncauses circuit interruption at each of the stationary contacts, apermanent magnet disposed below each stationary contact, the dispositionof each magnet being such that the magnet axes are parallel and theother at the other side of the plunger and the disposition being suchthat their axes are parallel with like poles directed in oppositedirections and with one stationary'contact partly encircling one magnetand the other stationary contact partly encircling the other magnet,pole shoes disposed at the ends of each magnet so projectingtransversely of the magnets that one pair of pole shoes of one magnetstraddles one stationary contact and the other pair of pole shoes of theother magnet straddles the other stationary contact to provide magneticarc blowout fields directed in oppositedirections transversely of therespective stationary contacts to effect are blowout at each stationarycontact when the contact on the plunger is moved to circuitinterruption, and the curvature of each of the stationary'contactspartly. encircling the magnets provide arc horns to aid in lengtheningthe arcs at the stationary contacts and thus expedite V blowout of thearcs.

3. An electric switch comprising, a housing, a plunger slidably mountedin said housing, a spring biased elongated contact mounted transverselyof the plunger on the plunger to move with movement of the plunger, apair of stationary contacts mounted in the housing, one stationarycontact being disposed at one side of the plunger and the other at theother side of the plunger and so disposed with reference to theelongated contact and the plunger that movement of the plunger in onedirection causes circuit closure at each of the stationary contacts andmovement of the plunger'in an opposite direction causes circuitinterruption at each of the stationary contacts, a pair of relativelyshort cylindrical ceramic permanent magnets of insulating materialmounted in spaced relation to each other in the housing one being at oneside of the plungerand the other at' the other side of the plunger andthe disposition being such that their axes are parallel with like polespointing in opposite directions, one stationary contact partly enandgenerally normal'to the direction of movement of the elongatedcontact'and the plunger with like poles of the magnets being directed inthe opposite directions, pole shoesv disposed at the ends of each of themagnets so projecting transversely of the magnet axes that one pair of'poles straddles one stationary contact and the other pair of polesstraddles the other stationary contact to provide a magnetic arc blowout,field in one direction transversely of one stationary contact and amagnetic arc blowout field in the opposite direction transversely of theother stationary contact whereby the magnets efiect arc blowout in thesame direction at each sta- V tionary contact when the elongated contacton the plunger is moved to circuit interruption. g

2. An electric switch comprising, a housing, a plunger slidably mountedin said housing, a spring biased elon- I gated contact mountedtransversely of the plunger on the plunger to move with movement of theplunger, a pair of stationary contacts mounted in the housing, onestationary contact being disposed at one side of the plunger andtheiother at the other side of the plunger and so disposed withreference to the elongated contact and the plunger that movement of theplunger in one direction causes circuit closure at each of thestationary.

contacts and movement of the plunger in an opposite directioncauses'circuit interruption at each of the sta-s tionary contacts, apair of relatively short cylindrical permanent magnets mounted in spacedrelation to each other in the housing, one being at one side oftheplunger circling one magnet and the other stationary contact partlyencircling the other magnet, pole shoes 'at the ends of'the'magnets sotransversely projecting from the magnet ends as to straddle thestationary contacts, whereby the magnets eifect arc blowout in the same.direction ateach stationary contact when the elongated contact on theplunger is moved to circuit interruption and the curvature of thestationary contact partly encircling the magnets form are horns to aidin lengthening the arc and thus expedite blowout of the arcs.

4. An electric switchcomprising, a housing of insulating material, aplunger having a pair of spaced stops and being slidably mounted in saidhousing, an elongated electric contact member disposed on the plungeragainst one of the stops, a back-up member slidably mounted on theplunger and disposed against the other stop, a biasing springbetween'the back-up member and elongated contact member to thus bias theback-up membet and elongated contact member against the stops, a-

pair of stationary contact members mounted in the housing, a biasingspring for the plunger for normally biasing the plunger and thus theelongated contact member on the plunger in sucha direction that themovable elongated contact member does not bridge the stationary contactmembers, means on said housing for selectively securing said back-upmember in either of two positions namely, in one position the switch isanormally open switch and in another position the switch is a normallyclosed switch, whereby longitudinal movement of the plunger mayselectively effect either contact closure or contact interruption, apermanent magnet under each stationary contact member with the magnetsdisposed transversely of the ends of the elongated contact memher on theplunger with like poles directed in the opposite direction, whereby themagnets, on interruption of an electric current by the switch, blows thearcs out by lengthening both arcs in the same direction with referenceto the stationary contact members.

5. An electric switch comprising, a housing of insulating material, aplunger having a pair of spaced stops and being slidably mounted in saidhousing, an elongated electric contact member disposed on the plungeragainst one of the stops, a back-up member slid'ably mounted on theplunger and disposed against the other stop, a biasing spring betweenthe back-up member and elongated contact member to thus bias the back-upmember and elongated contact member against the stops, a pair ofstationary contact members mounted in the housing, a biasing spring forthe plunger for normally biasing the plunger and thus the elongatedcontact member on the plunger in such a direction that the movableelongated contact member does not bridge the stationary contact members,means on said housing for selectively securing said back-up member ineither of two positions namely, in one position the switch is a normallyopen switch and in another position the switch is a normally closedswitch, whereby longitudinal movement of the plunger may selectivelyefiect either contact closure or contact interruption, a permanentmagnet under each stationary contact member with the'magnets disposedtransversely of the ends of the elongated contact member on the plungerwith like poles directed in the opposite direction, pole shoes at theends of the magnets having portions projecting transversely of the endsof the magnets so as to straddle the sationary contact members, wherebythe magnets, on interruption of an electric current by the switch, blowsthe arcs out by lengthening both arcs in the same direction withreference to the stationary contact members.

UNITED STATES PATENTS 752,552 Hewlett Feb. 16, 1904 2,153,402 TritleApr. 4, 1939 2,337,949 Walle Dec. 28, 1943 2,571,951 Schaelchlin Oct.16, 1951 2,629,035 Yingst Feb. 17, 1953 2,822,450 Goudy et a1 Feb. 4,1958 2,846,528 Burrell Aug. 5, 1958 2,896,043 Andrews July 21, 1959FOREIGN PATENTS 136,167 Australia Feb. 1, 1950

